9-16
The pressure in chamber(32)(pilot pressure)becomes equal to the tank pressure[ 0 Kgf/㎠(0 psi)]
because chamber(32) is connected with chamber(5). The pilot spool is then shifted rightward and
passages(29 and 30) are connected with each other.Consequently the pressure in check valve spring
chamber(26) becomes high enough to hold the piston steady and the check valve poppet (D)
completely closes the cylinder circuit.In this state,fluid leaks through port C are prevented by the
check valve poppet seat and also by friction surfaces of the pilot spool and the spool (H)(unloading
valve 2), because check valve spring chamber (24) and chamber (23) of spool(H)(unloading valve 2)
Are connected with each other through passage(27).That is,leaks from chamber(24) to passage (25)
are prevented by the check valve poppet seat,those from chamber(33) to chambers(32 and 34) by the
friction surface of pilot spool(F),and those from chamber(23) to port T4 by the friction surface of
spool (H) (unloading valve 2)
2) Lifting position
Fig.9-25
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